1. Field of the Invention
The present invention relates generally to an indexable insert for cutting processing and a cutting tool having the indexable insert. More specifically, it relates to an indexable insert and a cutting tool having the indexable insert suitable for inner diameter processing of a small hole or a very small hole in a small-sized component such as a component for OA equipment, an electronic component, or a small diameter bearing.
2. Description of the Prior Art
Conventionally used as an inner diameter processing tool have been a throwaway type in which a chip 22 is fastened to a front end of a holder 21 so as to be attachable or detachable as shown in FIG. 6 and a brazing type in which a chip 32 is fastened by brazing to a front end of a holder 31 as shown in FIG. 7.
The brazing type requires a lot of time to replace the chip 32 when the chip's edge is damaged, which is not economical. Accordingly, the throwaway type is currently used in most cases.
The throwaway type is generally used for processing a large-diameter hole in a large-sized component such as an automobile component, however, this type is not used for processing a very small-diameter hole in a small-sized component such as a component for OA equipment or an electronic component. A solid cutting tool as shown in FIG. 8 is generally used for processing the very small-diameter hole.
Referring to FIG. 8, the integral cutting tool is constituted by a chip 45 and a sleeve 46 for supporting the chip 45 by fastening. The chip 45 is generally formed by cutting a cylindrical member, so that a cutting edge 44 and a holder 43 are integrally composed of the same material.
The chip 45 of such a solid type has a structure in which the holder 43 is inserted into the sleeve 46, and is fixed to the sleeve 46 by tightening a set bolt (not shown) from the outside of the sleeve 46.
In such a structure, a force for the sleeve 46 to clamp the indexable insert 45 is weak, so that chatter vibration is liable to be generated in the chip 45. The repetition accuracy of the cutting edge 44 is low. Further, the diameter at a front end of the sleeve 46 is larger than that of the cutting edge 44 of the chip 45, so that a front end surface of the sleeve 46 expands in a collar shape toward the chip 45. Therefore, the front end surface of the sleeve 46 is positioned so as to close a hole of a work piece at the time of inner diameter cutting processing, resulting in poor cutting chip discharge properties. Further, when the sleeve 46 is used, undercut processing cannot be performed.